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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 4th Dec 2019, 11:32 am   #1
Welsh Anorak
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Default Sony turntable motor weak

Hi
I'm renovating an oldish Sony music centre (HP211) and the turntable motor is not strong enough. It works from a tap on the mains transformer. No voltage is given in the manual, but it's around 140v which I think is OK. It spins freely and the coils haven't overheated. However it struggles to turn the platter and when it finally gets up to speed 33rpm records play perfectly - at the 45rpm setting! It can be easily stopped by hand. Besides lubrication is there anything else I can do? It's a simple AC induction motor.
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Old 4th Dec 2019, 12:06 pm   #2
Nickthedentist
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Default Re: Sony turntable motor weak

Puzzling!

Do we know for sure that this definitely worked once? First thoughts are that possibly the wrong motor has been fitted, i.e. one that's designed to run directly from the UK mains.
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Old 4th Dec 2019, 12:24 pm   #3
'LIVEWIRE?'
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Default Re: Sony turntable motor weak

As a U.K spec motor would be under - voltaged by at least 39&, your theory sounds right, Nick. Having said that, I'd be reluctant to run it from a higher voltage, unless there was any way I could confirm that it was indeed a 230/240v motor.
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Old 4th Dec 2019, 1:00 pm   #4
vidjoman
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Default Re: Sony turntable motor weak

It appears to be a 110 volt motor with an idler drive to the turntable. Have you cleaned the drive and turntable rim?
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Old 4th Dec 2019, 3:56 pm   #5
wave solder
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Default Re: Sony turntable motor weak

Without seeing a diagram I assume it's a standard shaded pole motor? It's not a capacitor run motor is it?
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Old 4th Dec 2019, 4:07 pm   #6
vidjoman
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Default Re: Sony turntable motor weak

From the circuit diagram I saw on the internet the motor is not shown - just the connection from the transformer showing a separate 110 volt winding going to a socket marked motor.
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Old 4th Dec 2019, 4:20 pm   #7
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Default Re: Sony turntable motor weak

I saw that, The record deck TTS-312 is a separate service manual.
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Old 4th Dec 2019, 10:04 pm   #8
Welsh Anorak
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Default Re: Sony turntable motor weak

Hi
Thanks for your ideas. It's a standard shaded pole motor, no run caps or anything like that. It runs OK on its own but is easy to stop by hand. I wouldn't say the unit's been apart before and everything's original and typically Sony of the period. The platter's quite heavy, but there's no question of the idler slipping; the motor just stalls.
I vaguely remember the Grundig TK120 series of tape recorders having a lazy motor, but lubricating and running it brought it back to life. As Nick says, puzzling!
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